Bluebulb Projects' The Measure of Things presents:
120 is about one-and-one-tenth times the number of Elements on the Periodic Table.
In other words, it's 1.02 times the count of Elements on the Periodic Table, and the count of Elements on the Periodic Table is 0.98 times that amount.
(a.k.a. Periodic Table of the Elements, a.k.a chemical elements) (confirmed elements as of 2016)